U.S. patent number 6,136,936 [Application Number 08/486,602] was granted by the patent office on 2000-10-24 for ethylene copolymers, process for the preparation of ethylene-based polymers and catalyst system used therein.
This patent grant is currently assigned to Montell Technology Company B.V.. Invention is credited to Enrico Albizzati, Giulio Balbontin, Tiziano Dall'Occo, Luigi Resconi.
United States Patent |
6,136,936 |
Dall'Occo , et al. |
October 24, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Ethylene copolymers, process for the preparation of ethylene-based
polymers and catalyst system used therein
Abstract
Ethylene copolymers are prepared with comonomers selected from:
(a) .alpha.-olefins, (b) cycloolefins and (c) polyenes, with a
content of ethylene units of between 80 and 99 mol %, a content of
units derived from .alpha.-olefin, cycloolefin and/or polyene
comonomers of between 1 and 20 mol %, characterized in that: (a) in
TREF (Temperature Rising Elution Fractionation) analysis, a
quantity equal to at least 90% by weight of the copolymer is eluted
within a temperature interval of less than 50.degree. C., and (b)
M.sub.w /M.sub.n >3, where M.sub.w is the weight-average
molecular weight and M.sub.n is the number-average molecular
weight, both determined by means of GPC.
Inventors: |
Dall'Occo; Tiziano (Ferrara,
IT), Resconi; Luigi (Ferrara, IT),
Balbontin; Giulio (Ferrara, IT), Albizzati;
Enrico (Arona, IT) |
Assignee: |
Montell Technology Company B.V.
(NL)
|
Family
ID: |
11369136 |
Appl.
No.: |
08/486,602 |
Filed: |
June 7, 1995 |
Foreign Application Priority Data
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Jun 20, 1994 [IT] |
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MI94A1279 |
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Current U.S.
Class: |
526/348.6;
526/160; 526/348; 526/348.3; 526/348.2 |
Current CPC
Class: |
C08F
210/02 (20130101); C08F 210/16 (20130101); C08F
10/02 (20130101); C08F 210/16 (20130101); C08F
4/61927 (20130101); C08F 10/02 (20130101); C08F
4/61927 (20130101); C08F 4/61916 (20130101); Y10S
526/943 (20130101); C08F 210/18 (20130101); C08F
4/61912 (20130101); C08F 4/61927 (20130101); C08F
110/02 (20130101); C08F 110/02 (20130101); C08F
2500/07 (20130101); C08F 210/16 (20130101); C08F
210/08 (20130101); C08F 2500/12 (20130101); C08F
210/16 (20130101); C08F 232/00 (20130101); C08F
2500/25 (20130101); C08F 210/16 (20130101); C08F
210/08 (20130101); C08F 210/14 (20130101); C08F
2500/12 (20130101); C08F 2500/17 (20130101); C08F
210/18 (20130101); C08F 232/00 (20130101); C08F
236/00 (20130101); C08F 2500/25 (20130101) |
Current International
Class: |
C08F
210/00 (20060101); C08F 210/02 (20060101); C08F
210/16 (20060101); C08F 4/00 (20060101); C08F
110/00 (20060101); C08F 4/619 (20060101); C08F
110/02 (20060101); C08F 4/6192 (20060101); C08F
210/18 (20060101); C08F 010/08 (); C08F
010/14 () |
Field of
Search: |
;526/348.6,348,348.2,348.3,160 |
References Cited
[Referenced By]
U.S. Patent Documents
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Other References
Hawley's Condensed Chemical Dictionary, 11th E,D. Van Nostrand
Reinhold, New York, 1987, 352, 1083-1084. .
Kelusky, et al., Polymer Engineering and Science, vol. 27, No. 20,
pp. 1562-1571 (1987). .
Chen, et al., "(1,3-Propanediyl) silylene-bis(1-indenyl)
dichlorozirconium. Synthesis and polymerization catalysis." Journal
of Organometallic Chemistry, vol. 487, pp. 29-34 (1995). .
"Comparison of zirconocene and hafnocene catalysts for the
polymerization of ethylene and 1-butene"; K. Heiland, and W.
Kaminsky; Makromol. Chem., vol. 193, pp. 601-610 (1992). .
"Determination of Branching Distributions in Polyethlne and
Ethylene Copolymers"; L. Wild, T.R. Ryle, D.C. Knobeloch, and I.R.
Peak; J. Polymer Science: Polymer Physics Edition, vol. 20, pp.
441-455 (1982). .
"Electronic Effects in Homogeneous Idenylzirconium Ziegler-Natta
.
Catalysis"; N. Piccolrovazzi, P. Pino, G. Consiglio, A. Sironi, and
M. Moret; Organometallics, vol. 9, pp. 3098-3105 (1990). .
"Crystal Structures and Stereospecific Propylene Polymerization
with Chiral Hafnium Metallocene Catalysis"; J.A. Ewen, L.
Haspeslagh, J.L. Atwood, and H. Zhang; Am. Chem. Soc., vol. 109,
pp. 6544-6545 (1987)..
|
Primary Examiner: Wu; David W.
Assistant Examiner: Choi; Ling-Siu
Attorney, Agent or Firm: Bryan Cave LLP Stiefel, Esq.;
Maurice B.
Claims
What is claimed is:
1. An ethylene copolymer with at least one comonomer selected from
the group consisting of propylene, 1-butene, 1-pentene,
4-methyl-1-pentene, 1-hexene, 1-octene, 4,6-dimethyl-1-heptene,
1-decene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene or
allylcyclohexane, said copolymer having a content of ethylene units
of from 80 to 99 mol % and a content of said comonomer units of
between 1 and 20 mol %, said copolymer having the following
characteristics:
(a) in TREF (Temperature Rising Elution Fractionation) analysis, a
quantity equal to at least 90% by weight of the copolymer is eluted
in a temperature interval of less than 50.degree. C.;
(b) M.sub.w /M.sub.n >4, where M.sub.w is the weight average
molecular weight and M.sub.n is the number-average molecular
weight, both determined by GPC; and
(c) no more than one melting point is detectable by differential
scanning calorimetry analysis.
2. Ethylene copolymer according to claim 1, wherein the value of
the ratio of the melt index F/E is greater than 100, where F is
measured according to I.sub.21 :ASTM D-1238 with a load of 21.6 kg,
while E is measured according to I.sub.2 :ASTM D-1238 with a load
of 2.16 kg.
3. Ethylene copolymer according to claim 1, having a density of
less than 0.94 g/cm.sup.3.
4. Ethylene copolymer according to claim 1, having a solubility of
less than 10% by weight in xylene at 25.degree. C.
5. Ethylene copolymer according to claim 1, wherein the comonomer
is 1-butene.
6. An ethylene copolymer with 1-butene with a content of units
derived from 1-butene of between 1 and 20 mol %, wherein
(a) the percentage by weight of 1-butene (%B) determined by .sup.13
C-NMR analysis, and the density (D) (in g/ml) of the copolymer
satisfy the following relationship:
(b) M.sub.w /M.sub.n >4, where M.sub.w is the weight average
molecular weight and M.sub.n is the number average molecular
weight, both determined by GPC analysis; and
(c) no more than one melting point is detectable by DSC
analysis.
7. A copolymer of ethylene and at least one comonomer selected
from
(a) .alpha.-olefins of the formula CH.sub.2 .dbd.CH--CH.sub.2 R,
where R is hydrogen or a linear, branched or cyclic alkyl radical
having 1 to 20 carbon atoms,
(b) cycloolefins, and
(c) polyenes,
said copolymer having a content of ethylene units of from 80 to 99
mol % and a content of said .alpha.-olefin, cycloolefin and/or
polyene comonomer of between 1 and 20 mol %, said copolymer having
the following characteristics:
(a) in TREF (Temperature Rising Elution Fractionation) analysis, a
quantity equal to at least 90%, by weight of the copolymer is
eluted in a temperature interval of less than 50.degree. C.;
(b) M.sub.w /M.sub.n >5, where M.sub.w is the weight average
molecular weight and M.sub.n is the number-average molecular
weight, both determined by GPC; and
(c) no more than one melting point is detectable by differential
scanning calorimetry analysis.
8. The copolymer of ethylene according to claim 7 wherein the value
of the ratio of the melt index F/E, where the condition F involves
a load of 21.6 kg, while the condition E involves a load of 2.16
kg, is greater than 100.
9. The copolymer of ethylene according to claim 7 having a density
of less than 0.94 g/cm.sup.3.
10. The copolymer of ethylene according to claim 7 having a
solubility of less than 10%, by weight, in xylene at 25.degree.
C.
11. The copolymer of ethylene according to claim 7 wherein the
comonomer is 1-butene.
12. The copolymer of ethylene according to claim 11 wherein the
percentage by weight of 1-butene (%B) determined by .sup.13 C-NMR
analysis, and the density (D) (in g/ml) of the copolymer satisfy
the relationship
13. An ethylene copolymer comprising ethylene and from 1 mol % to
20 mol % of a comonomer selected from the group of comonomers
consisting of cycloolefins, polyenes and cc-olefins of the formula
CH.sub.2 .dbd.CH--CH.sub.2 R, wherein R is hydrogen or a linear,
branched or cyclic alkyl radical having 1 to 20 carbon atoms, and
having a M.sub.w /M.sub.n >5 wherein M.sub.w is the
weight-average molecular weight and M.sub.n is the number-average
molecular weight both determined by GPC, and having a single
melting point detectable by DSC measurement, and wherein a quantity
of the copolymer equal to at least 90% by weight is eluted in a
temperature interval of less than 50.degree. C. in TREF
analysis.
14. A copolymer according to claim 13 wherein the comonomer is
selected from the group consisting of propylene, 1-butene,
1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene,
4,6-dimethyl-1-heptene, 1-decene, 1-dodecene, 1-tetradecene,
1-hexadecene, 1-octadecene, 1-eicosene and allylcyclohexane.
15. A copolymer according to claim 13 or 14 wherein the copolymer
comprises ethylene and propylene.
16. A copolymer according to claim 13 wherein the copolymer
comprises ethylene and 1-butene.
17. A copolymer according to claim 13 wherein the copolymer
consists of ethylene and 1-butene.
18. A copolymer according to claim 16 or 17 wherein the percentage
by weight of 1-butene (%B) determined by .sup.13 C-NMR analysis,
and the density (D) (in g/ml) of the copolymer satisfy the
relationship %B+285 D.ltoreq.272.
19. A copolymer according to claim 13 wherein the comonomer is a
cycloolefin.
20. A copolymer according to claim 19 wherein the comonomer is
selected from the group consisting of cyclopentene, cyclohexene and
norborene.
21. A copolymer according to claim 13 wherein the comonomer is a
polyene.
22. A copolymer according to claim 21 wherein the comonomer is
selected from the group consisting of 1,4-hexadiene, isoprene,
1,3-butadiene, 1,5-hexadiene and 1,6-heptadiene.
23. A copolymer according to claim 13 wherein the comonomer is in
an amount of between 2 mol % to 15 mol %.
24. A copolymer according to claim 23 wherein the comonomer is in
an amount of 15 mol %.
25. A copolymer according to claim 23 wherein the copolymer has a
melt index F/E of at least about 50 where F is measured according
to I.sub.21 :ASTM D-1238 with a load of 21.6 kg, while E is
measured according to I.sub.2 :ASTM D-1238 with a load of 2.16
kg.
26. A copolymer according to claim 25 wherein the copolymer has a
melt index F/E of greater than 100 where F is measured according to
1.sub.21 :ASTM D-1238 with a load of 21.6 kg, while E is measured
according to I.sub.2 :ASTM D-1238 with a load of 2.16 kg.
27. A copolymer according to claim 13 wherein the copolymer has a
melt index F/E of between about 50 and 188 where F is measured
according to I.sub.21 :ASTM D-1238 with a load of 21.6 kg, while E
is measured according to I.sub.2 :ASTM D-1238 with a load of 2.16
kg.
28. A copolymer according to claim 13 wherein the copolymer has a
density of less than 0.94 g/cm.sup.3.
29. A copolymer according to claim 28 wherein the copolymer has a
density of less than 0.92 g/cm.sup.3.
30. A copolymer according to claim 13 wherein the copolymer has a
melting point of less than 120.degree. C.
31. A copolymer according to claim 30 wherein the copolymer has a
melting point of less than 109.degree. C.
32. A copolymer according to claim 31 wherein the copolymer has a
melting point of less than 100.degree. C.
Description
The present invention relates to ethylene copolymers and in
particular to ethylene copolymers provided with a uniform
distribution of the comonomer units within the polymer chain and
with a wide molecular weight distribution. This invention also
relates to a process for the preparation of ethylene-based polymers
and to the catalytic system used in this process.
It is known that polyethylene can be modified by the addition,
during the polymerization reaction, of small quantities of
.alpha.-olefins, generally 1-butene, 1-hexene or 1-octene. This
gives LLDPE (linear low density polyethylene) copolymers which have
short branches along the main chain due to the units derived from
the .alpha.-olefin comonomers.
These branches have the effect that the degree of crystallinity and
hence the density of the copolymer turn out to be lower than in the
polyethylene homopolymer. Typically, the LLDPE copolymers have
densities of the order of 0.910-0.940 g/cm.sup.3. Consequently, the
LLDPE copolymers have optimum mechanical properties, in particular
for the production of films.
The lowering of the degree of crystallinity and of the density of
the copolymers is a function of the type and quantity of the
incorporated .alpha.-olefin. In particular, the greater the
quantity of incorporated .alpha.-olefin, the lower are the
resulting degrees of crystallinity and density.
The properties of the copolymer depend, apart from the type and
quantity of the incorporated .alpha.-olefin comonomer, also on the
distribution of the branches along the polymer chain. In
particular, the greater uniformity of the distribution of the
branches has a positive effect on the properties of the copolymers.
In fact, with the same type and quantity of incorporated
.alpha.-olefin, a higher uniformity of distribution allows lower
degrees of crystallinity and density to be obtained.
LLDPE copolymers prepared with conventional Ziegler-Natta catalysts
are characterized by a poor uniformity of composition distribution,
and in particular by the presence of consecutive units of
comonomers in the polymer chain and by long sequences of ethylene
units. To obtain copolymers with sufficiently low density and
crystallinity, it is therefore necessary to use large quantities of
.alpha.-olefin comonomer.
The use of catalysts based on metallocene compounds has made it
possible to obtain LLDPE copolymers having an improved uniformity
of composition. These copolymers, of the same chemical composition,
are endowed with superior properties as compared with traditional
copolymers.
The copolymers obtained with metallocene catalysts have, however, a
narrow molecular weight distribution (MWD). This expresses itself
in poor processability properties, and this can be disadvantageous
in particular in some applications, such as the use for films.
With the purpose of overcoming this disadvantage, processes for the
preparation of LLDPE copolymers have been proposed, which are
carried out in the presence of a catalyst consisting of a
metallocene compound and a non-metallocene titanium compound.
U.S. Pat. No. 4,701,432 describes, for example, the preparation of
LLDPE in the presence of a catalytic component consisting of
bis(cyclopentadienyl)zirconium dichloride and titanium
tetrachloride, supported on silica.
European Patent Application EP 439,964 describes the preparation of
LLDPE in the presence of a catalyst consisting of a metallocene
compound and a compound based on titanium, magnesium and a
halogen.
Nevertheless, the LLDPE copolymers thus obtained, though having a
broad molecular weight distribution, do not have a satisfactory
distribution of the comonomers within the polymer chain.
Another proposed system is that which provides for the use of
catalysts consisting of two different metallocene compounds.
K. Heiland and W. Kaminsky in "Makromol. Chem. 193, 601-610 (1992)"
describe the copolymerization reaction of ethylene with 1-butene in
the presence of a catalyst consisting of a mixture of
rac-ethylenebis(indenyl)zirconium dichloride and
rac-ethylenebis(indenyl)hafnium dichloride. The copolymers obtained
with this catalyst are provided with a substantially bimodal
molecular weight distribution. Nevertheless, the regularity in the
distribution of the comonomers across the various polymer chains
does not yet reach a high level. This is due to the fact that the
values of the copolymerization parameters r.sub.1 and r.sub.2,
characteristic of the zirconocene and hafnocene used, differ widely
from one another, as reported on page 607 of the above
publication.
It would therefore be desirable to obtain an LLDPE copolymer which
has an extremely uniform distribution of the comonomer units in the
polymer chain and at the same time a broad molecular weight
distribution.
Stereorigid metallocenes are generally prepared as a mixture of the
racemic and meso form. The meso form is generally removed by
separation from the rac/meso mixtures, since only the chiral
racemic form is stereospecific. Only a few disclosures are known of
the use of the meso form in the polymerization of olefins.
European Patent Application EP 584,609 discloses the use of a
particular class of bridged bis-indenyl metallocenes in the meso
form or in a meso/rac mixture for the preparation of atactic
polyolefins having high molecular weight and a narrow molecular
weight distribution (M.sub.w /M.sub.n .ltoreq.4). In particular,
homo- and copolymers of propylene were prepared.
European Patent Application EP 643,078 describes the preparation of
ethylene-based polymers endowed with very high molecular weights
and narrow molecular weight distribution, by carrying out the
polymerization reaction in the presence of a metallocene-based
catalyst wherein the metallocene is stereorigid and it is in its
meso isomeric form.
Surprisingly, the applicant has now found that it is possible to
prepare LLDPE copolymers having a uniform distribution of the
comonomer units along the polymer chain and a broad molecular
weight distribution, as well as other ethylene-based polymers, by
carrying out the polymerization reaction in the presence of a
catalyst consisting of a mixture of the racemic and meso isomers of
a stereorigid metallocene compound.
An object of the present invention is therefore an ethylene
copolymer with at least one comonomer selected from:
(a) .alpha.-olefins of the formula CH.sub.2 .dbd.CH--CH.sub.2 R,
where R is hydrogen or a linear, branched or cyclic alkyl radical
having 1 to 20 carbon atoms,
(b) cycloolefins and
(c) polyenes,
with a content of units derived from .alpha.-olefin, cycloolefin
and/or polyene comonomers of between 1 and 20 mol %, preferably
between 2 and 15 mol %, characterized in that:
(a) in TREF (Temperature Rising Elution Fractionation) analysis, a
quantity equal to at least 90% by weight of the copolymer is eluted
in a temperature interval of less than 50.degree. C., and
(b) M.sub.w /M.sub.n >3, where M.sub.w is the weight-average
molecular weight and M.sub.n is the number-average molecular
weight, both determined by GPC.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the result of the TREF analysis of an
ethylene/1-butene copolymer according to the invention.
FIG. 2 shows the result of the TREF analysis of an
ethylene/1-butene copolymer prepared by the method described by K.
Heiland and W. Kaminsky in the article cited above.
FIG. 3 shows the result of the TREF analysis of an
ethylene/1-hexene copolymer according to the invention.
The TREF analysis, carried out as described by L. Wild, T. R. Ryle,
D. C. Knobeloch and I. R. Peak in J. Polymer Science: Polymer
Physics Edition, Vol. 20, 441-455 (1982), provides information on
the length of the ethylene sequences and consequently on the
distribution of the comonomer units within the polymer chain.
In fact, this method makes it possible to fractionate the
copolymers on the basis of their crystallisability and hence on the
basis of the ethylene sequences between two branches due to the
.alpha.-olefin units present in the chain. The more uniform the
distribution of the .alpha.-olefin units, the more restricted is
the resulting temperature interval, in which the polymer is
eluted.
The molecular weights of the copolymers of the invention are
distributed within a relatively wide interval.
One indication of the molecular weight distribution is given by the
ratio M.sub.w /M.sub.n which, for the copolymers of the invention,
is generally greater than 3, preferably greater than 4 and more
preferably greater than 5.
Further information on the molecular weight distribution in the
copolymers of the invention is obtainable from the measurement of
the melt index. In particular, the values of the ratio of the melt
indices F/E, where the condition F involves a load of 21.6 kg,
while the condition E involves a load of 2.16 kg, prove to be high.
For MIE values of about 0.4, there are values of the MIF/MIE ratio
which are generally higher than 50, preferably higher than 70 and
more preferably higher than 100.
The resulting melting point of the copolymers of the invention,
which is a function of the type and quantity of comonomer, is
generally below 120.degree. C. and can reach values below
100.degree. C.
The resulting density of the copolymers of the invention, which is
also a function of the type and quantity of comonomer, is generally
below 0.94 g/cm.sup.3 and can reach values below 0.90
g/cm.sup.3.
In particular, according to another aspect of the present
invention, the latter relates to an ethylene copolymer with
1-butene with a content of units derived from 1-butene of between 1
and 20 mol %, characterized in that
(a) the percentage by weight of 1-butene (%B), determined by
.sup.13 C-NMR analysis, and the density (D) of the copolymer
satisfy the following relationship:
(b) M.sub.w /M.sub.n >3, where M.sub.w is the weight-average
molecular weight and M.sub.n is the number-average molecular
weight, both determined by GPC.
The copolymers according to the invention are further characterized
by relatively low values of the solubility in xylene at 25.degree.
C., which are generally below 10% by weight and can reach values
below 5% by weight.
The copolymers of the invention have values of intrinsic viscosity
(I.V.) generally higher than 0.5 dl/g and preferably higher than
1.0 dl/g. The intrinsic viscosity can reach values of 2.0 dl/g and
beyond.
Examples of .alpha.-olefins of the formula CH.sub.2
.dbd.CH--CH.sub.2 R which can be used as comonomers in the
copolymers of the invention are propylene, 1-butene, 1-pentene,
4-methyl-l-pentene, 1-hexene, 1-octene, 4,6-dimethyl-1-heptene,
1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene,
1-eicosene and allylcyclohexane. Preferably, 1-butene, 1-hexene or
1-octene and more preferably 1-butene are used.
Examples of cycloolefins are cyclopentene, cyclohexene and
norbornene.
The copolymers can also contain units derived from polyenes, in
particular conjugated or non-conjugated linear or cyclic dienes
such as, for example, 1,4-hexadiene, isoprene, 1,3-butadiene,
1,5-hexadiene and 1,6-heptadiene.
In the case of polyenes other than non-conjugated
.alpha.,.omega.-diolefins having 6 or more carbon atoms, these are
preferably used in quantities of between 0 and 3 mol % as a second
.alpha.-olefin comonomer.
A further object of the present invention is a process for the
preparation of ethylene polymers, comprising the polymerization
reaction of ethylene in the presence of a catalyst consisting of
the reaction product of:
(A) a mixture of the racemic and meso isomers of a stereorigid
metallocene compound of a transition metal, belonging to Groups
III, IV or V or the lanthanides in the Periodic Table of the
Elements, with two cyclopentadienyl ligands connected to each other
by a chemical bridge, and
(B) at least one co-catalyst capable of activating both the racemic
form and the meso form of the metallocene compound, selected from
the alumoxanes and the compounds capable of forming an
alkylmetallocene cation.
The ethylene polymerization reaction can be carried out in the
presence of at least one comonomer selected from .alpha.-olefins of
the formula CH.sub.2 .dbd.CH--CH.sub.2 R, where R is a linear,
branched or cyclic alkyl radical having 1 to 20 carbon atoms,
cycloolefins and/or polyenes. In this way, it is possible to
prepare ethylene copolymers which are the subject of the present
invention.
The racemic form and the meso form of the metallocene compound are
present in a weight ratio of between 99:1 and 1:99
respectively.
Stereorigid metallocene compounds which can be used in the process
of the present invention are those of the formula (I): ##STR1## in
which M is a metal selected from Ti, Zr and Hf, the substituents
R.sup.1 are C.sub.1 -C.sub.20 -alkyl radicals, C.sub.3 -C.sub.20
-cycloalkyl radicals, C.sub.2 -C.sub.20 -alkenyl radicals, C.sub.6
-C.sub.20 -aryl radicals, C.sub.7 -C.sub.20 -alkylaryl radicals or
C.sub.7 -C.sub.20 -arylalkyl radicals and can contain atoms of Si
or Ge;
the substituents R.sup.2 and R.sup.3 are hydrogen atoms, C.sub.1
-C.sub.20 -alkyl radicals, C.sub.3 -C.sub.20 -cycloalkyl radicals,
C.sub.2 -C.sub.20 -alkenyl radicals, C.sub.6 -C.sub.20 -aryl
radicals, C.sub.7 -C.sub.20 -alkylaryl radicals or C.sub.7
-C.sub.20 -arylalkyl radicals and can contain atoms of Si or Ge; if
the substituents R.sup.2 are other than hydrogen, the substituents
R.sup.1 and R.sup.2 on the same cyclopentadienyl can form a ring
containing 5 to 20 carbon atoms;
R.sup.4 is a divalent group selected from (CR.sup.5.sub.2).sub.n,
(SiR.sup.5.sub.2).sub.n, (GeR.sup.5.sub.2).sub.n, NR.sup.5 or
PR.sup.5, where the substituents R.sup.5 which can be equal or
different are C.sub.1 -C.sub.20 -alkyl radicals, C.sub.3 -C.sub.20
-cycloalkyl radicals, C.sub.2 -C.sub.20 -alkenyl radicals, C.sub.6
-C.sub.20 -aryl radicals, C.sub.7 -C.sub.20 -alkylaryl radicals or
C.sub.7 -C.sub.20 -arylalkyl radicals and, if R.sup.4 is
(CR.sup.5.sub.2).sub.n, (SiR.sup.5.sub.2).sub.n, or
(GeR.sup.5.sub.2).sub.n, two substituents R.sup.5 on the same
carbon, silicon or germanium atom can form a ring containing 3 to 8
atoms, n being an integer of between 1 and 4, preferably 1 or
2;
the substituents X.sup.1 and X.sup.2 are hydrogen or halogen atoms,
R.sup.6, OR.sup.6, SR.sup.6, NR.sup.6.sub.2 or PR.sup.6.sub.2,
where the substituents R.sup.6 which can be equal or different are
C.sub.1 -C.sub.20
-alkyl radicals, C.sub.3 -C.sub.20 -cycloalkyl radicals, C.sub.2
-C.sub.20 -alkenyl radicals, C.sub.6 -C.sub.20 -aryl radicals,
C.sub.7 -C.sub.20 -alkylaryl radicals or C.sub.7 -C.sub.20
-arylalkyl radicals and can contain atoms of Si or Ge.
Those sterorigid metallocene compounds are preferred which are of
the formula (II) ##STR2## and of the formula (III) ##STR3## where,
in the formulae (II) and (III), M, R.sup.3, R.sup.4, X.sup.1 and
X.sup.2 are as defined above and the substituents R.sup.7 are
hydrogen, C.sub.1 -C.sub.10 -alkyl radicals, C.sub.3 -C.sub.10
-cycloalkyl radicals, C.sub.2 -C.sub.10 -alkenyl radicals, C.sub.6
-C.sub.10 -aryl radicals, C.sub.7 -C.sub.10 -alkylaryl radicals or
C.sub.7 -C.sub.10 -arylalkyl radicals and can contain atoms of Si
or Ge and, furthermore, two adjacent substituents R.sup.7 can form
a ring having 5 to 8 carbon atoms.
Those stereorigid metallocene compounds of the formula (II) or
(III) are particularly suitable in which M is Zr, the substituents
R.sup.3 are hydrogen atoms or C.sub.1 -C.sub.2 -alkyl, the
substituents R.sup.7 are hydrogen or methyl groups, the
substituents X.sup.1 and X.sup.2 are chlorine or methyl groups and
the group R.sup.4 is a (CH.sub.2).sub.2 or Si(CH.sub.3).sub.2
radical.
Non-limiting examples of metallocenes suitable for use in the
process according to the present invention are:
______________________________________ C.sub.2 H.sub.4 (Ind).sub.2
MCl.sub.2 C.sub.2 H.sub.4 (Ind).sub.2 MMe.sub.2 C.sub.2 H.sub.4
(Ind).sub.2 M(NMe.sub.2).sub.2 C.sub.2 H.sub.4 (H.sub.4 Ind).sub.2
MCl.sub.2 C.sub.2 H.sub.4 (H.sub.4 Ind).sub.2 MMe.sub.2 C.sub.2
H.sub.4 (H.sub.4 Ind).sub.2 M(NMe.sub.2)OMe Me.sub.2 Si(Ind).sub.2
MCl.sub.2 Me.sub.2 Si(Ind).sub.2 MMe.sub.2 Ph(Me)Si(Ind).sub.2
MCl.sub.2 Ph.sub.2 Si(Ind).sub.2 MCl.sub.2 C.sub.2 Me.sub.4
(Ind).sub.2 MCl.sub.2 Me.sub.2 SiCH.sub.2 (Ind).sub.2 MCl.sub.2
C.sub.2 H.sub.4 (2-MeInd).sub.2 MCl.sub.2 C.sub.2 H.sub.4
(4,7-Me.sub.2 Ind).sub.2 MCl.sub.2 C.sub.2 H.sub.4 (5,6-Me.sub.2
Ind).sub.2 MCl.sub.2 C.sub.2 H.sub.4 (2,4,7-Me.sub.3 Ind).sub.2
MCl.sub.2 C.sub.2 H.sub.4 (2-MeH.sub.4 Ind).sub.2 MCl.sub.2 C.sub.2
H.sub.4 (4,7-Me.sub.2 H.sub.4 Ind).sub.2 MCl.sub.2 C.sub.2 H.sub.4
2,4,7-Me.sub.3 H.sub.4 Ind).sub.2 MCl.sub.2 C.sub.2 H.sub.4
(Benz[e]Ind).sub.2 MCl.sub.2 C.sub.2 H.sub.4
(2-Me-Benz[e]Ind).sub.2 MCl.sub.2 Me.sub.2 Si(2-MeInd).s ub.2
MCl.sub.2 Me.sub.2 Si(4,7-Me.sub.2 Ind).sub.2 MCl.sub.2 Me.sub.2
Si(5,6-Me.sub.2 Ind).sub.2 MCl.sub.2 Me.sub.2 Si(2,4,7-Me.sub.3
Ind).sub.2 MCl.sub.2 Me.sub.2 Si(2-MeH.sub.4 Ind).sub.2 MCl.sub.2
Me.sub.2 Si(4,7-Me.sub.2 H.sub.4 Ind).sub.2 MCl.sub.2 Me.sub.2
Si(2,4,7- Me.sub.3 H.sub.4 Ind).sub.2 MCl.sub.2 Me.sub.2
Si(Benz[e]Ind).sub.2 MCl.sub.2 Me.sub.2 Si(2-Me-Benz[e]Ind).sub .2
MCl.sub.2 ______________________________________
where Me=methyl, Cp=cyclopentadienyl, Ind=indenyl, Ph=phenyl,
H.sub.4 Ind=4,5,6,7-tetrahydroindenyl and M is Ti, Zr or Hf,
preferably Zr.
A particularly preferred metallocene compound for use in the
process according to the present invention is
ethylene-bis(4,7-dimethyl-1-indenyl)zirconium dichloride.
The molar ratio between the aluminium of the alumoxane and the
metal of the metallocene compound is generally between about 5:1
and about 10000:1, and preferably between about 20:1 and about
5000:1.
Alumoxanes which can be used in the process according to the
invention are, for example, those which are linear, branched or
cyclic and contain at least one group of the type (IV): ##STR4##
where the substituents R.sup.8 which can be equal or different are
R.sup.1 or a group --O--Al(R.sup.8).sub.2 and, if appropriate, some
R.sup.8 can be halogen atoms.
In particular, alumoxanes of the formula (V): ##STR5## where n is 0
or an integer of between 1 and 40, in the case of linear compounds,
or alumoxanes of the formula (VI): ##STR6## with n being an integer
of between 2 and 40, in the case of cyclic compounds, can be
used.
Those alumoxanes are particularly suitable for use according to the
present invention in which the radicals R.sup.1 are methyl groups,
that is to say the methyl alumoxanes (MAO). These can be obtained
by reacting trimethylaluminium (TMA) with water.
Non-limiting examples of compounds for the formation of an
alkylmetallocene cation are compounds of the formula Y.sup.+
Z.sup.-, where Y.sup.+ is a Bronsted acid capable of donating a
proton and irreversibly reacting with a substituent X.sup.1 or
X.sup.2 of the compound of the formula (I), and Z.sup.- is a
compatible anion which does not co-ordinate and which is capable of
stabilizing the active catalytic species resulting from the
reaction of the two compounds and which is sufficiently labile for
being displaceable by an olefinic substrate. Preferably, the anion
Z.sup.- consists of one or more boron atoms. More preferably, the
anion Z.sup.- is an anion of the formula BAr.sub.4.sup.(-), where
the substituents Ar which can be identical or different are aryl
radicals such as phenyl, pentafluorophenyl or
bis(trifluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate is
particularly preferred. Moreover, compounds of the formula
BAr.sub.3 can conveniently be used. Compounds of this type are
described, for example, in the International Published Patent
Application WP 92/00333, the content of which is to be incorporated
in the present description by reference.
The catalysts which can be used in the process of the invention can
furthermore contain one or more metalorganic compounds of aluminium
of the formula AlR.sup.9.sub.3 or Al.sub.2 R.sup.9.sub.6, in which
the substituents R.sup.9 which can be equal or different are
defined as the substituents R.sup.1 or are hydrogen or halogen
atoms.
Non-limiting examples of aluminium compounds of the formula
AlR.sup.9.sub.3 or Al.sub.2 R.sup.9.sub.6 are:
Al(Me).sub.3, Al(Et).sub.3, AlH(Et).sub.2, Al(iBu).sub.3,
AlH(iBu).sub.2, Al(iEs).sub.3, Al(C.sub.6 H.sub.5).sub.3,
Al(CH.sub.2 C.sub.6 H.sub.5).sub.3, Al(CH.sub.2 CMe.sub.3).sub.3,
Al(CH.sub.2 SiMe.sub.3).sub.3, Al(Me).sub.2 iBu, Al(Me).sub.2 Et,
AlMe(Et).sub.2, AlMe(iBu).sub.2, Al(Me).sub.2 iBu, Al(Me).sub.2 Cl,
Al(Et).sub.2 Cl, AlEtCl.sub.2 and Al.sub.2 (Et).sub.3 Cl.sub.3,
where Me methyl, Et=ethyl, iBu=isobutyl and iEs=isohexyl. Trimethyl
aluminium (TMA) and triisobutylaluminium (TIBAL) are preferred.
The catalysts employed in the process of the present invention can
advantageously be used on inert supports. These are obtained by
depositing the metallocene compound or the product of the reaction
thereof with the co-catalyst or the co-catalyst and subsequently
the metallocene compound on inert supports such as, for example,
silica, alumina, styrene/divinylbenzene copolymers or
polyethylene.
A particularly suitable class of inert supports which can be used
in the process of the present invention, are porous organic
supports which are functionalized by groups with active hydrogen
atoms. Those are particularly preferred in which the organic
support is a partially crosslinked styrene polymer. These supports
are described in the Italian Patent Application No. MI93A001467,
whose content is to be incorporated in the present description by
reference.
The solid compound thus obtained, in combination with the further
addition of an alkylaluminium compound, either as such or
prereacted with water, can also be used in gas-phase
polymerization.
The ethylene polymerization process according to the present
invention can be carried out not only in the gas-phase but also in
the liquid phase, in the presence of an inert aromatic hydrocarbon
solvent such as, for example, toluene, or preferably, in an
aliphatic solvent such as, for example, propane or n-hexane.
The polymerization temperature is generally between 0.degree. C.
and 200.degree. C., in particular between 20.degree. C. and
100.degree. C., and more particularly between 30.degree. C. and
80.degree. C.
The polymerization yields depend on the purity of the metallocene
component of the catalyst. The metallocene compounds obtained by
the process of the invention can therefore be used as such or be
subjected to a purification treatment.
The components of the catalyst can be brought into contact with one
another before the polymerization. The contact time is generally
between 1 and 60 minutes, preferably between 5 and 20 minutes.
The examples which follow are given for illustrative purposes and
do not restrict the invention.
CHARACTERIZATIONS
The presence of functional groups on the supports is confirmed by
IR analysis. The quantitative determination of the functional
groups containing active hydrogen atoms is carried out by
gas-volumetric measurement after reaction with
triethylaluminium.
The porosity and the surface areas are determined by nitrogen
adsorption by the BET method, using a SORPTOMATIC 1900 instrument
from Carlo Erba, and by mercury porosimetry using a Porosimeter
2000 from Carlo Erba.
The intrinsic viscosity (IV) is measured in tetralin at 135.degree.
C.
The melt index (MI) is measured under the following conditions:
condition E (I.sub.2 :ASTM D-1238) at 190.degree. C. with a load of
2.16 kg;
condition F (I.sub.21 :ASTM D-1238) with a load of 21.6 kg; the
melt flow ratio (MFR) is equal to the F/E ratio.
The content of comonomer units in the copolymers is determined by
.sup.13 C-NMR analysis carried out by means of a Bruker 200 MHz
instrument, using C.sub.2 D.sub.2 Cl.sub.4 as solvent, at a
temperature of 110.degree. C.
The ratio of meso to racemic form for the metallocene compound was
determined by .sup.1 H-NMR spectra carried out in CDCl.sub.3 at
25.degree. C. and taking as reference the signal of CDCl.sub.3 at
7.25 ppm. The peak of the meso form is a 2.54 ppm and the peak of
the racemic form is a 2.72 ppm. From the ratio of the areas
deriving from the peaks it was obtained the ratio meso/racemic
form.
The absolute density is determined by immersion of a sample of
extruded copolymer in a column with a density gradient according to
the ASTM D-1505 method.
The apparent bulk density (ABD) was determined by the method of DIN
53194.
The measurements by differential scanning calorimetry (DSC) were
carried out on a DSC-7 instrument from the Perkin Elmer Co. Ltd.
according to the following procedure. About 10 mg of sample are
heated to 180.degree. C. at a scanning rate equal to 10.degree.
C/minute; the sample is held for 5 minutes at 180.degree. C. and
then cooled at a scanning rate equal to 10.degree. C./minute. A
second scanning is then carried out according to the same procedure
as the first. The values reported are those obtained in the second
scanning.
The solubility in xylene at 25.degree. C. was determined according
to the following procedures. About 2.5 g of polymer and 250 ml of
xylene are placed into a flask fitted with a cooler and ref lux
condenser and maintained under a blanket of nitrogen. It is heated
at 135.degree. C. with stirring for about 60 minutes. It is allowed
to cool down to 25.degree. C. with stirring. It is filtered and,
after evaporation of the solvent from the filtrate to constant
weight, the weight of the soluble material is obtained.
The TREF analyses were carried out using an apparatus equipped with
two stainless steel columns having internal dimensions of
800.times.26 mm, which are connected to one another by a U-junction
and packed with a bed consisting of small silanized glass spheres.
The sample is dissolved in o-xylene (stabilized with 0.03% by
weight of Irganox 1010 antioxidant) in a concentration of 7.5 mg/ml
at a temperature of 140.degree. C. The solution obtained is charged
to the columns maintained at 125.degree. C. and then cooled
according to the following sequence: 125-90.degree. C. in 30
minutes, 90-10.degree. C. in 14 hours. After the cooling, a
continuous elution with o-xylene is carried out at 10 ml/minute,
the fractions being collected every 20 minutes. During the elution,
the temperature of the column is slowly raised from 10.degree. C.
to 103.degree. C. at a rate of 0.15.degree. C./minute, and then
from 103.degree. C. to 125.degree. C. at a rate of 2.2.degree.
C/minute.
PREPARATION OF THE SUPPORTS
Polystyrene Resin
An aqueous solution consisting of:
11 l of distilled water,
400 ml of a 5% by weight solution of ROAGIT SVM (Rohm) in
water,
55.5 g of PROLIT C10 (Caffaro) and
11 g of sodium chloride
was introduced in an atmosphere of nitrogen into a glass reactor of
30 l capacity, fitted with a thermometer, reflux condenser, rod
stirrer and thermocontrol system. This was stirred (350 r.p.m.) for
1 further hour at room temperature, and an organic solution
consisting of
5.55 l of n-octane,
1.85 l of toluene,
1.55 l of styrene,
2.55 l of 64% divinylbenzene in ethylvinylbenzene and
74 g of 75% dibenzoyl peroxide in water was then introduced.
The temperature of the reactor was taken to 80.degree. C. within 1
hour, maintained for 8 hours and then taken back to room
temperature. The product obtained was subjected to repeated
washings with distilled water, extraction with methanol at
50.degree. C. and subsequently to drying at 100.degree. C. under a
residual pressure of 1 mm Hg. This gave 2.7 kg of product of
microspheroidal morphology, having the following
characteristics:
Surface area: 370 m.sup.2 /g (BET), 126 m.sup.2 /g (Hg), Porosity:
1.74 ml/g (BET), 1.92 ml/g (Hg), Mean pore radius: 94 .ANG. (BET),
305 .ANG. (Hg),
______________________________________ Particle size distribution
(PSD): ______________________________________ 0.8% >300 .mu.m;
2.2% 300-250 .mu.m; 7.0% 250-180 .mu.m; 10.5% 180-150 .mu.m; 73.2%
150-106 .mu.m; 5.5% 106-75 .mu.m; 0.8% <75 .mu.m;
______________________________________
Preparation Of The Functionalized Support (A1)
(a) Acylation
300 ml of carbon disulphide and 30 g of the polystyrene resin were
introduced under a nitrogen atmosphere into a glass reactor of 750
ml capacity fitted with a thermometer, reflux condenser, rod
stirrer and a thermocontrol system. After setting a constant
temperature of 12.degree. C., 66 g (0.49 mol) of previously ground
AlCl.sub.3 and then, within 1 hour, 32 ml of freshly distilled
CH.sub.3 COCl were added. The temperature was then taken to
25.degree. C. and maintained for 6 hours under stirring. The
mixture was then transferred with constant stirring into a 3 l
flask
containing a mixture of about 1 kg of ground ice and 300 ml of HCl
(37%), and stirred for a further 30 minutes. The resin recovered
after filtration was subjected to repeated washings with distilled
water and then with acetone and finally with methanol. After
drying, this gave 34 g of product of spheroidal morphology. The
I.R. spectrum showed a band centered at 1685 cm.sup.-1 attributable
to carbonyl.
(b) Reduction
15.2 g of the acetylated resin obtained under (a), 100 ml of
dioxane, 100 ml of distilled water and 15 g of NaBH.sub.4 were
introduced into a glass reactor of 500 ml capacity fitted with a
thermometer, reflux condenser and rod stirrer. The mixture was
continuously stirred for 50 hours at a temperature of 25.degree.
C., and a further 4 g of NaBH.sub.4 were then added, stirring being
continued for another 70 hours. The resin recovered after
filtration was subjected to repeated washings with distilled water,
then with acetone and finally with methanol. After drying, 13.4 g
of a product of spheroidal morphology were recovered. The IR
spectrum showed a broadened band centered on 3440 cm.sup.-1,
attributable to hydroxyl while the carbonyl band at 1685 cm.sup.-1
was much reduced compared with that of the resin obtained under
(a). The hydroxyl group content, determined by gas-volumetric
titration with triethylaluminium, was found to be 3.3 meq per gram
of resin.
Preparation Of The Functionalized Support (A2)
(a) Acylation
4300 ml of methylene chloride and 225 g of the polystyrene resin
were introduced into a reactor of 6 liters capacity, fitted with a
mechanical stirrer and a thermostat system. The mixture was cooled
to 10.degree. C., and 580 g of (previously ground) AlCl.sub.3 were
rapidly added. While maintaining the internal temperature at
10.degree. C., 230 ml of acetyl chloride were added dropwise within
1 hour. The reaction mixture was continuously stirred at 25.degree.
C. for a further 24 hours. The reaction mixture was carefully
poured into a suspension consisting of 2160 ml of distilled H.sub.2
O, 2160 g of ice and 2160 ml of 37% HCl solution. After the end of
the addition, stirring was continued for another 30 minutes and the
solid residue was then filtered off and washed repeatedly with
distilled H.sub.2 O and then with acetone and subsequently
methanol. The product obtained was dried at 60.degree. C.; 260 g of
product were recovered. The IR spectrum showed a band centered on
1680 cm.sup.-1, belonging to the carbonyl group.
(b) Reduction
1060 ml of methanol and 260 g of the acylated resin obtained under
(a) were introduced into a 3-liter flask fitted with a mechanical
stirrer, thermometer and a thermostat system. While maintaining the
temperature of the suspension at below 350C, a solution consisting
of 138 g of NaBH.sub.41 170 ml of NaOH (20%) and 1060 ml of
distilled water was fed in the course of 2 hours. The mixture was
allowed to react for 48 hours at 25.degree. C. and then 200 ml of
acetone were slowly added in order to destroy the excess
NaBH.sub.4. The resin was filtered off and then repeatedly washed
with, in this order distilled water, acetone, methanol and acetone.
The product was dried in vacuo at 600C for 24 hours. 234 g of
product were recovered. The IR analysis showed a broadened band
centered on 3440 cm.sup.-1, while the carbonyl band at 1680 had
disappeared. The hydroxy group content was determined by
gas-volumetric titration with triethyl-A, giving 1.9 meq per gram
of resin. The particles of spherical shape show a mean dimension of
150 .mu.m with the following characteristics of surface area and
porosity: 327 m.sup.2 /g and 0.7 ml/g with a mean pore diameter of
43 .ANG. (Sorptomatic 1900 BET porosimeter) and 144 m.sup.2 /g and
1.53 ml/g with pores of 212 .ANG. (Hg).
PREPARATION OF THE CATALYTIC COMPONENTS
rac/meso-Ethylene-Bis (4,7-Dimethyl-Indenyl) Zirconium
Dichloride
(a) Preparation of 4,7-dimethylindene
The synthesis was carried out according to the method described in
"Organometallics, 1990, 9, 3098" (54% yield on p-xylene).
(b) Preparation of 1,2-bis(4,7-dimethyl-3-indenyl)ethane
38.2 g (265 mmol) of 4,7-dimethylindene were dissolved in 350 ml of
tetrahydrofuran, and the temperature of the solution was taken to
0.degree. C. 165 ml of n-butyllithium (1.6 M in hexane, 264 mmol)
were then added dropwise drop over 2.5 hours. After returning to
room temperature and continued stirring for 4 hours, a red-purple
solution of 4,7-dimethylindenyllithium was obtained. This solution
was cooled to -70.degree. C. and treated dropwise in the course of
35 minutes with 25.3 g of 1,2-dibromoethane (135 mmol) in 15 ml of
tetrahydrofuran. After returning to room temperature, this gave a
clear yellow solution, to which water was added. The organic phase
was collected and dried over Na.sub.2 SO.sub.4. The solvent was
then evaporated in vacuum, 20 g of product (48% yield) being
obtained.
(c) Preparation of
rac/meso-ethylene-bis(4,7-dimethyl-1-indenyl)zirconium dichloride
(B1)
A suspension of 10 g of 1,2-bis(4,7-dimethylindenyl)ethane (31.8
mmol) in 80 ml of tetrahydrofuran was added by means of a cannula
to a solution of 2.82 g of KH (70.3 mmol) in 160 ml of
tetrahydrofuran under constant stirring. After cessation of the
evolution of hydrogen, the resulting brown solution was separated
from the excess KH. This solution and a solution of 12 g of
ZrCl.sub.4 (THF).sub.2 (31.8 mmol) in 250 ml of tetrahydrofuran
were added dropwise in the course of 3 hours by means of a cannula
to a flask containing 50 ml of rapidly stirred tetrahydrofuran. A
yellow solution and a precipitate were formed. After removal of the
solvent in vacuum, the yellow-orange residue (mixture of the
racemic and meso isomers in a ratio of 2.33:1 according to .sup.1
H-NMR analysis) was subjected to extraction with CH.sub.2 Cl.sub.2
until all the orange product was completely dissolved. The yellow
solid (1.7 g) proved to be a single stereoisomer, namely the meso
(11.3% yield). After evaporation of the CH.sub.2 Cl.sub.2 from the
orange solution, 4.9 g of a yellow-orange solid corresponding to a
mixture of 93.7% of the racemic isomer and 6.3% of the meso isomer,
as determined by .sup.1 H-NMR analysis, were obtained.
(d) Preparation of
rac/meso-ethylene-bis(4,7-dimethyl-1-indenyl)zirconium dichloride
(B2)
The procedure as under (c) was followed, but the extraction with
CH.sub.2 Cl.sub.2 was continued until 5.1 g of yellow-orange solid
corresponding to a mixture of 90.6% of the racemic isomer and 9.4%
of the meso isomer, as determined by .sup.1H -NMR analysis, were
obtained.
(e) Preparation of
rac-ethylene-bis(4.7-dimethyl-1-indenyl)zirconium dichloride
(B3)
1.0 g of the solid product obtained under (c) was subjected to
recrystallization from toluene at -20.degree. C. 0.3 g of crystals
of orange colour were separated off, which were found to be
composed of pure rac-ethylene-bis(4,7-dimethyl-1-indenyl)zirconium
dichloride, as determined by .sup.1 H-NMR analysis.
Ethylene-Bis(Indenyl)Hafnium/Zirconium Dichloride
(a) Preparation of 1.2-bisindenylethane
The preparation described by J. Ewen in J. Am. Chem. Soc., 1987,
109, 6544, Suppl. mat., was followed.
50.8 g of indene (437 mmol) were dissolved under an inert
atmosphere in 500 ml of tetrahydrofuran in a 2-necked 2 l flask and
cooled to -78.degree. C. 175 ml of n-butyllithium (2.5 M in hexane,
437.5 mmol) were added dropwise slowly (1 hour). The mixture was
allowed to warm again to room temperature and was stirred for a
further 4 hours. It was cooled to -78.degree. C., and 40.42 g of
1,2-dibromoethane (215 mmol) dissolved in 100 ml of tetrahydrofuran
were added dropwise (within 20 minutes). After the end of the
addition, the temperature was taken to 50.degree. C., stirring was
continued for 12 hours, and the mixture was then allowed to cool to
room temperature, and 20 ml of water were added. The organic phase
was dried and the residue was extracted with pentane. Evaporation
in vacuum gave 28.65 g of product (yield=51.6%).
(b) Preparation of ethylene-bis(indenyl)hafnium
dichloride/ethylene-bis (indenyl )zirconium dichloride
7.13 g (27.8 mmol) of 1,2-bisindenylethane and 50 ml of anhydrous
tetrahydrofuran were placed into a two-necked 250 ml flask. The
yellow solution was cooled to -78.degree. C. and 34.5 ml of
n-butyllithium (1.6 M in hexane, 55.2 mmol) were added. This gave a
reddish-brown solution which was heated under reflux for one minute
and then allowed to cool to room temperature.
8.84 g of anhydrous HfCl.sub.4 (Strem product, 2.7% of Zr) (27.6
mmol) were placed into a four-necked flask fitted with a cooler and
dissolved at a temperature of -180.degree. C. in 70 ml of
tetrahydrofuran. The solution was then heated under reflux for 30
minutes, giving a brown-violet suspension which was allowed to cool
to ambient temperature with vigorous stirring.
The solution of the lithium salt of bisindenylethane was then added
in about 2 minutes and stirring was continued for 2 hours and 30
minutes. The solution obtained became brown-yellow in colour.
Bubbling in gaseous HCl gave a yellow-orange suspension. The
solvent was removed in vacuo, 100 ml of ethyl ether were added and
the mixture was left overnight at 0.degree. C. The residue filtered
off from the ethereal solution, was dried in vacuum and extracted
with 3 times 100 ml of methylene chloride.
The solution was concentrated to 30 ml, causing yellow
microcrystals to precipitate which were filtered off.
This gave 1.15 g of product which .sup.1 H-NMR analysis showed to
consist of 96% of ethylene-bis(indenyl)hafnium dichloride and 4% of
ethylene-bis(indenyl)zirconium dichloride.
Methylalumoxane (Mao)
A commercial product (Schering, now Witco, MW 1400) was used in a
30% by weight solution in toluene. After removal of the volatile
fractions in vacuo, the semicrystalline material was crushed until
a white powder was obtained which was further treated in vacuo (0.1
mmHg) for 4 hours at a temperature of 40.degree. C.
Triisobutylaluminium (Tibal)
A commercial product (Schering, now Witco) was used in a 20%
weight-volume solution in hexane.
POLYMERIZATIONS
All the operations to prepare catalysts were carried out in an
atmosphere of anhydrous nitrogen.
EXAMPLE 1
(a) Preparation of the supported catalyst
100 ml of anhydrous toluene and 5.2 g of the support (A1) were
introduced into a glass reactor of 350 ml capacity, fitted with a
thermometer, reflux condenser, rod stirrer and a thermocontrol
system. 30 ml of a 1 M toluene solution of MAO (157 mg of Al/g of
support) was added within 40 minutes to the mixture at a constant
temperature of -5.degree. C. with continued stirring. The reaction
was allowed to proceed for 1 hour at a temperature of -5.degree.
C., then for 1 hour at a temperature of 0.degree. C., for 1 hour at
30.degree. C. and then for 4 hours at a temperature of 80.degree.
C. After cooling to 25.degree. C., the solid residue was filtered
off and washed with 100 ml of toluene and redispersed in 100 ml of
toluene. It was then cooled to 0.degree. C., and 50 ml of a toluene
solution containing 224.2 mg of the mixture of
rac/meso-ethylene-bis(4,7-dimethyl-indenyl)zirconium dichloride
(B1) (8.3 mg of Zr/g of support) were added in 55 minutes. The
temperature was taken to 30.degree. C., and the mixture was stirred
for a further 2 hours. This gave a suspension of reddish colour
which was allowed to settle, giving a precipitate and a colourless
solution which was removed by syphoning. The precipitate was
repeatedly washed with anhydrous toluene and then dried in vacuum.
7.0 g of a product of microspheroidal morphology were recovered,
having the following composition by weight: 9.6% of Al, 0.7% of Cl,
0.44% of Zr.
(b) Polymerization
A steel autoclave of 2.5 l capacity, fitted with a rod stirrer with
magnetic drive, a manometer, a temperature indicator, a catalyst
feed system, monomer feed lines and a thermostat jacket was cleaned
by washing with propane at 70.degree. C. At ambient temperature, 5
mmol of TIBAL in 5 ml of hexane, 1260 ml of propane and the
quantities of ethylene, 1-butene and hydrogen indicated in Table 1
were introduced, and the reactor was heated to 45.degree. C.
The catalyst suspension was prepared in a Schlenck-type test tube
with a drain cock at the bottom. 5 mmol of TIBAL in 5 ml of hexane
and then 92 mg of the supported catalyst obtained under (a) were
successively introduced at a temperature of 25.degree. C.
The reagents were left in contact for 5 minutes, and the suspension
was then introduced into the autoclave by excess ethylene
pressure.
The temperature was then taken to 50.degree. C. and maintained
constant for the duration of the polymerization. The total pressure
was kept constant by feeding an ethylene/1-butene mixture in a
molar ratio equal to 18. The polymerization was stopped by
introducing 0.6 l (STP) of CO into the autoclave after cooling to
30.degree. C.
The reactor was allowed to degas slowly, and the polymer obtained
was dried at 60.degree. C. in vacuum.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLE 2
(a) Preparation of the supported catalyst
300 ml of toluene and 30.2 g of the support (A2) were introduced
into a jacketed reactor of 750 ml capacity, fitted with a rod
stirrer, thermometer, reflux condenser and thermocontrol
system.
The suspension was thermostatically controlled at -10.degree. C.,
and 200 ml of a solution of 0.9 M of MAO (160 mg of Al/g of
support) were added in 70 minutes. The mixture was kept for 60
minutes at -10.degree. C., for 60 minutes at 0.degree. C., for 60
minutes at 30.degree. C. and for 240 minutes at 80.degree. C. The
suspension was filtered at 50.degree. C. and subjected to 2
washings with 200 ml of anhydrous toluene and finally dried in
vacuum. 66.8 g of spheroidal particles containing 7.5% by weight of
Al and 27.0% by weight of solvent were recovered.
100 ml of anhydrous toluene and 4.9 g of the spheroidal particles
obtained were introduced into a jacketed reactor of 350 ml capacity
fitted with a rod stirrer, thermometer, reflux condenser and a
thermocontrol system.
The suspension was cooled to 0.degree. C., and 30 ml of a toluene
solution containing 0.1 g of the mixture of
rac/meso-ethylene-bis(4,7-dimethyl-indenyl)zirconium dichloride
(B1) (6.1 mg of Zr/g of support) were added in 30 minutes.
The suspension of red-orange colour was stirred for a further 3
hours at 30.degree. C. After decanting from the solid, the liquid
was filtered and the residue was subjected to 2 washings with 100
ml of toluene and 2 washings with 100 ml of hexane and was finally
dried in vacuum at 25.degree. C. 3.6 g of product of
microspheroidal morphology, having the following composition by
weight: 8.7% of Al, 0.98% of Cl, 0.36% of Zr, were recovered.
(b) Polymerization
The procedure described under (b) in Example 1 was followed, using
105 mg of the supported catalyst obtained under (a).
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLE 3
(a) Preparation of the supported catalyst
The procedure described under (a) in Example 2 was followed, but
using 9.6 mg of Zr/g of support. 3.3 g of product of
microspheroidal morphology, having the following composition by
weight: 8.6% of Al, 1.05% of Cl, 0.44% of Zr, were recovered.
(b) Polymerization
The procedure described under (b) in Example 1 was followed, using
106 mg of the supported catalyst obtained under (c).
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2. The result
of the TREF analysis is indicated in FIG. 1.
EXAMPLE 4
(a) Preparation of the supported catalyst
The procedure described under (a) in Example 2 was followed, but
using the mixture of
rac/meso-ethylene-bis(4,7-dimethyl-indenyl)zirconium dichloride
(B2) (7.8 mg of Zr/g of support) in place of the mixture (B1). 5.4
g of product of a microspheroidal morphology, having the following
composition by weight: 8.1% of Al, 1.09% of Cl, 0.44% of Zr, were
recovered.
(b) Polymerization
The procedure described under (b) in Example 1 was followed, using
267 mg of the supported catalyst obtained under (a).
The polymerization conditions are indicated in Table 1, while the
data relative to the polymer are indicated in Table 2.
EXAMPLE 5
The procedure described under (b) in Example 1 was followed, but in
the absence of TIBAL and using MAO (4.2 mmol of Al) and 0.5 mg of
the mixture (B1) for preparing the catalyst.
The polymerization conditions are indicated in Table 1, while the
data relative to the polymer are indicated in Table 2.
EXAMPLE 6
The procedure of the preceding example was followed, but using 0.1
mmol of MAO and adding 5 mmol of TIBAL to the autoclave.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLES 7-8
(For Comparison)
The procedure followed was as in Example 5, but in the absence of
MAO and using 2.1 mmol of TIBAL and 1.0 mg of the metallocene (B3).
1.05 mmol of H.sub.2 O were then added to the autoclave.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLE 9
(For Comparison)
The procedure followed was as in Example 5, but using 4.7 mmol of
MAO and, in place of the mixture (B1), 1.0 mg of a mixture
consisting of 96% of ethylene-bis(indenyl)hafnium dichloride and of
4% of ethylene-bis(indenyl)zirconium dichloride.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are related in Table 2. The result of
the TREF analysis is indicated in FIG. 2.
EXAMPLE 10
The procedure described under (b) in Example 1 was followed, but
carrying out the polymerization reaction at a temperature of
70.degree. C., using 0.95 l of anhydrous hexane in place of
propane, and 42 mg of the supported catalyst obtained under
(a) in Example 3.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLE 11
The procedure of the preceding example was followed, but carrying
out the polymerization reaction at a temperature of 80.degree. C.
and using 16.4 mg of supported catalyst.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLE 12
(a) Preparation of the supported catalyst The procedure described
under (a) in Example 2 was followed, but using the mixture of
rac/meso-ethylene-bis(4,7-dimethyl-indenyl)zirconium dichloride
(B2) (7.8 mg of Zr/g of support) in place of the mixture (B1). 5.4
g of product of microspheroidal morphology, having the following
composition by weight: 8.1% of Al, 1.09% of Cl, 0.44% of Zr, were
recovered.
(b) Polymerization
A steel autoclave of 2.5 liters capacity, fitted with a rod stirrer
with magnetic drive, manometer, temperature indicator, catalyst
feed system, a monomer feedline and a thermostat jacket, was
cleaned by washing with propane at 70.degree. C.
At ambient temperature, 280 ml of anhydrous 1-hexene (distilled
over LiAlH.sub.4), 5 mmol of TIBAL in 5 ml of hexane, 640 ml of
propane and the monomer quantities indicated in Table 1 were
introduced, and the reactor was then heated to 55.degree. C.
The catalyst suspension was prepared separately by adding, in a
vial with bottom discharge, 5 mmol of TIBAL in 5 ml of hexane and
190 mg of the supported catalyst obtained under (a) at a
temperature of 25.degree. C.
The components were left in contact for 5 minutes at ambient
temperature, before they were introduced into the autoclave by
excess ethylene pressure.
The temperature was raised to 60.degree. C. and kept constant
during the polymerization run. The total pressure was maintained
constant during the run by continuously feeding ethylene.
The polymerization was stopped by introducing 0.6 l (STP) of CO
into the autoclave, followed by rapid cooling to 30.degree. C. The
reactor was allowed to degas slowly, and the polymer obtained was
dried at 60.degree. C. in vacuum.
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2. The result
of the TREF analysis is indicated in FIG. 3.
EXAMPLE 13
(a) Preparation of the supported catalyst
The procedure followed was as described under (a) in Example 12,
but using 12.2 mg Zr/g of support. 5.6 g of product of
microspheroidal morphology, having the following composition by
weight: 9.3% of Al, 1.03% of Cl, 0.51% of Zr, were recovered.
(b) Polymerization
The procedure described under (b) in Example 12 was followed, but
using 132 mg of the supported catalyst obtained under (a).
The polymerization conditions are indicated in Table 1, while the
data relating to the polymer are indicated in Table 2.
EXAMPLE 14
A steel autoclave of 2.5 l capacity, fitted with a rod stirrer with
magnetic drive, manometer, temperature indicator, catalyst feed
system, monomer feedlines and a thermostat jacket, was cleaned by
washing with ethylene at 70.degree. C. 5 mmol of TIBAL in 1070 ml
of hexane were introduced at ambient temperature into the autoclave
and, after heating to 70.degree. C. and pressurizing with 16.8 bar
of ethylene, 1.73 bar of hydrogen were introduced. The autoclave
was then cooled to 65.degree. C.
The catalyst suspension was prepared in a Schlenck-type test tube
with a discharge cock at the bottom. At a temperature of 25.degree.
C., 5 mmol of TIBAL in 5 ml of hexane and then 500 mg of the
supported catalyst obtained under (a) in Example 13 were added in
sequence. The components were left in contact for 5 minutes, and
the suspension was then introduced into the autoclave by excess
ethylene pressure.
The temperature was raised to 70.degree. C. and the total pressure
was kept constant by continuously feeding ethylene. After 100
minutes, the polymerization was stopped by cooling to 30.degree. C.
and introducing 0.6 l (STP) of CO.
The polymer suspension was filtered and the polymer obtained was
dried in an oven at 60.degree. C. in vacuum. This gave 440 g of
spheroidal granules having the following characteristics:
MIE(I.sub.2)=0.34
MFR=84
absolute density=0.9623 g/ml
ABD=0.35 g/ml
Tm=134.degree. C.
TABLE 1 ______________________________________ 1-butene ethylene
H.sub.2 time yield activity EXAMPLE (ml) (bar) (bar) (min) (g)
(kg/g of Zr/h) ______________________________________ 1 285 16.5
0.05 154 136 131.0 2 165 15.9 0.11 120 132 125.7 3 164 15.9 0.11
120 252 237.7 4 170 16.4 0.55 166 604 186.0 5 363 16.7 0.3 120 130
676.2 6 164 16.0 0.1 120 46 239.3 7 COMP. 370 16.8 0.38 120 350
910.3 8 COMP. 500 10.6 0.31 120 127 330.3 9 COMP. 117 17.6 0.2 120
63 90.7 10 204 31.1 0.13 120 200 538.5 11 210 33.5 0.11 120 68
471.1 12 280* 14.5 0.37 120 629 371.5 13 280* 14.6 0.56 240 335
86.3 ______________________________________ *1-hexene
TABLE 2
__________________________________________________________________________
Melt index DSC TREF [.eta.] I.sub.2 I.sub.21 1-Butene Density Tm
(II) AH.sub.r (.DELTA..degree. C./90%) XSRT EXAMPLE (dL/g) (g/10
min) (g/10 min) MFR (% by weight) (g/mL) (.degree. C.) (J/g)
M.sub.w /M.sub.n polymer) (% by weight)
__________________________________________________________________________
1 1.9 n.d. 3.37 -- 11.5 0.9062 98 71 5.8 40 1.8 2 1.53 0.1 18.8 145
9.0 0.9158 105 105 8.1 n.d. 1.6 3 1.49 0.2 30.1 188 9.8 0.9145 102
106 6.4 35 4.4 4 1.40 0.4 60.8 169 9.0 0.9177 107 80 6.9 n.d. 3.4 5
2.11 0.4 32.1 73 10.7 0.9140 96 94 4.2 45 5.4 6 2.01 0.77 44.3 58
8.2 0.9210 110 111 4.9 40 1.4 7 COMP. 1.46 0.4 16.8 40 9.2 0.9112
104 87 2.9 30 1.1 8 COMP. 1.25 4.0 83.5 21 11.5 0.9055 100 74 2.3
40 3.8 9 COMP. 1.40 2.82 113.9 40 13.1 0.9125 84/109 69 7.9 60 15.9
10 1.5 0.34 20.4 60 6.1 0.9225 115 127 3.7 n.d. 1.0 11 1.5 0.8 58.8
73 5.4 0.9276 118 138 4.3 n.d. 0.6 12 1.44 0.19 24.4 128 11.5*
0.9165 107 88 5.4 30 2.2 13 1.24 1.07 86.6 81 11.0 0.9195 108 115
6.9 n.d. n.d.
__________________________________________________________________________
n.d. = not determined *1hexene
* * * * *